This invention relates to everting membrane sampling devices and, more particularly, to everting membrane devices forming a progressive sampling volume along a borehole, pipe, or the like.
There are many instances where it is desired to progressively sample within a borehole, pipe, or the like, to determine a profile of fluids or fluid material in the borehole. It is also necessary to sometimes isolate a section of the borehole for fluid extraction or injection. These operations are done conventionally using straddle packers that are inserted to the desired position in the borehole and then expanded to seal against the borehole wall, leaving an exposed section of the borehole for sampling and/or isolation.
Straddle packers can be trapped in a borehole by material sloughing from the side of the borehole. Indeed, the action of the straddle packer can cause a slough that traps the device. This problem is aggravated in horizontal boreholes where the device may be supported by one side of the borehole during insertion and withdrawal, with concomitant wear and slough from the borehole wall.
Another problem with straddle packers is that each interval to be sampled or isolated requires a discrete placement of the packer. Each movement requires a retraction of the sealing members at an existing location and expansion of the members at a new location. It will be appreciated that this is a time consuming operation and each movement of the packer is subject to sloughing of the borehole wall.
U.S. Pat. No. 5,176,207, incorporated herein by reference, teaches an everting membrane system that overcomes many of the problems of straddle packers in movement through a borehole. The everting membrane "rolls" along the borehole wall and is not prone to cause sloughing of the wall and is relatively easy to remove if sloughing does occur since the membrane is flexible. As taught in the '207 patent, the everting membrane may be provided with absorbent material or sample volumes at discrete locations along the membrane, but these features must be prefabricated for use at predetermined locations along the borehole.
Accordingly, it would be desirable to provide for a continuous and progressive isolation and/or sampling along a borehole, pipe, or the like. This problem is addressed by the present invention and an everting membrane design enables a traveling sample/isolation volume to be defined.
It is one object of the present invention to provide a traveling sample/isolation volume.
It is another object of the present invention to provide for sampling along a traveling sample volume.
One other object of the present invention is to provide a traveling sample system to obtain a continuous plot of the material permeability and fluid properties along a borehole.
Additional objects, advantages, and novel features of the invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims